Exploring Fine Subpixel Spatial Resolution of Hybrid CMOS Detectors

TL;DR

This paper investigates the potential for achieving subpixel spatial resolution in hybrid CMOS detectors for X-ray detection by analyzing charge cloud patterns and comparing experimental data with simulations.

Contribution

It introduces a model for subpixel resolution in hybrid CMOS detectors and applies it to a prototype suitable for the Lynx X-ray surveyor.

Findings

Experimental results demonstrate subpixel resolution capabilities.

Simulation matches experimental charge cloud patterns.

Small pixel detectors can achieve enhanced spatial resolution.

Abstract

When an X-ray is incident onto the silicon absorber array of a detector, it liberates a large number of electrons, which tend to diffuse outward into what is referred to as the charge cloud. This number can vary from tens to thousands across the soft X-ray bandpass (0.1 - 10 keV). The charge cloud can then be picked up by several pixels, and forms a specific pattern based on the exact incident location of the X-ray. We present experimental results on subpixel resolution for a custom H2RG with 36 micron pixels, presented in Bray 2018, and compare the data to simulated images . We then apply the model simulation to a prototype small pixel hybrid CMOS detector (HCD) that would be suitable for the Lynx X-ray surveyor. We also discuss the ability of a small pixel detector to obtain subpixel resolution.